Telephone-exchange system.



E. R. GORWIN.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED AUG. l0, 191'2.

Patented Sept. 1, 191i 2 SHEETSSHEET 1.

wiwsnssns INVENTDR B. R. 00mm.

I TELEPHONE momma SYSTEM. APPLICATION FILED AUGLIO, 1912. P t t d S t 1 109 11 4, a an e ep 1, 1914.

2 SHEETS-SHEET 2.

F IG. 2

I ELMER R CORWIN W01 I WITNESSES INNTENTDR ATTORNEY UNITED s A Es PATENT @FFICE. f i

'ELME R R. CORWIN, or CHICAGQ; ILLINOIS, ASSIG-NDR, BY MEsNn ASSIGNMENTS, T0 rRANK B. COOK COMPANY, or CHICAGQ, ILLINOIS, A coRroRA'rIoN or ILLINOIS.

rnLn rnonn-nxcnanen SYSTEM.

specification of Letters Patent.

To all whom it may concern: I

"Be it known that I, ELME R. CoRwiN, citizen of the United States, residing at Chicago, in thecounty of Cook and State of Illinois, have invented a .certainnew and useful Improvement in Telephone-Exchange Systems, of which the'following is a full,

clear, concise, and exact description, refer ence being had to the accompanyingdrawings, forming a part ofthis specification.

My invention relates to telephone exchange systems and in its preferred embodiment includes much ofthe equipment disclosed in myco-pendi'ng applications Serial No. 714,415, filed August 10,- 1912, and Serial No. 714,416, filed August" 10, 1912, though the invention isnot to'be' limited to of such Ie'quipment. v p In practising my inventionl preferably employ selectorfswitches, each jcommon'toa switching mechanism for extending the ends the use plurality of lines,' f;or connecting; calling lineswith QPGIaFOISlIGSPOHSIYQ dev ces such as operators telephones, there being link connectors at the exchangepreferably adapt ed-to their line joining function Independently of these selector'switches', though I do not limit myself to thesecharacteristics in all embodiments ofthe invention. *1 make use of these selector switches not only for the purpose stated but also in the processof. extending calling lines into connection withcalled lines, the present embodiment of the invention including electro-magnetic of the link connectors into connection with calling and called lines. V I also desirably employ these selector switches for associat ing a suitable source or sources of ringing current with the link connectors thereby to enable the called subscribers to be signaled.

The signaling operation is desirably auto-.

matically or to some extent automatically performed and the disconnection of the ringing generator is also automatically'effected when the called subscriber responds and inasmuch as a selector switch which was employed 'to associate the operators telephone with a calling subscriber remains in service for these purposes the operators telephone would be out of commission during a part of these operations when it might well be employed in association with another calling line, were it not for the apparatus and system forming the subject matter of the present application. In order that the operators telephone may bereleased after the operator has performed her part of the work in extending a calling line into connection with a called line, I provide switching mechanismwhich will transfer her telephone (or other responsive device) from operative association with the selector switch which was initially employed into association with another selector switch so that her telephone may bensedby another calling subscriber this sw tching mechanism not interfering with the relationship which-the first selector sw tch previously had withthe link connectorwhich was employed for connecting the calling and called subscribers. As the Invention is preferably employed there are two such-selector switches for each" operators position and a switching device individual to each selector switch, each switch- .ing device being adapted toassociate the operators telephone with the selector switch associated with such device and also to dissociate such telephonefrom such selector switch. Either of these'switching devices is in that position in which the opera-' tors telephone is associated with the correspending selector switch while the other switching device is in such position as to dissociate the operators telephone from the selector switch corresponding thereto so that but one of these selector switches is set into operation when a call is initated while the other selector switch is maintained in condition to have the operators telephone transferred into association therewith when the first selector switch to be employed has performed its function in enabling the operator to answer the calling'subscriber and also to enable the operator to effect the connection' of a link connector with the calling and called lines and to initiate the establish unent of connection between the ringing gener'ator and the called line. I

1 will explain my invention more fully by'reference to the accompanying drawings 5 in which- Figures 1 and 2 taken collectively in their numerical order and with the conductors at .the top thereof in alinement, represent a.

telephone exchange system equipped in accordancewitli the invention, and Fig. 3 is a detail of construction.

In tlie"drawings I have shown two tele phone stations 120 and .190 whose lines extend to an exchange equipped in accordance p v Patented Sept. 1, 1914. Application filed August 10, 1912. Serial No. 714,417.

with the invention. Each station includes well known equipment comprising a telephone switch hook 1, a telephone receiver 2, a telephone transmitter 3, a signal bell 4, and a condenser 5. The telephone switch hook closes the bell bridge across the sides of its line when supporting the receiver, and closes the telephone bridge when the receiver is removed from the switch hook. Assuming that subscribers station No. 120 desires communication with subscriber-s station No. 190, the calling subscriber will remove his telephone receiver 2 from its switch hook 1 to open the bridge containing the signal hell 4- and condenser 5 and to close the metallically continuous bridge containing the telephone transmitter 3 and the telephone receiver 2. Circuit is thereupon established.

through the relay 6 which may be traced from the grounded terminal of this relaythrough its winding, the upper armature switch of ringing relay 7, and its normal contact (this relay being operated only when its, line is .a called line), the sides of the calling line, the lower armature switch' of relay 7 ,and its normal contact, next to the uppermost armature switch of relay 8 and its contact,the relay 9, to the grounded bat- 'tery; 10,- the 'battery. 10 also-supplying talk-- ingcurrentto the transmitters. Thefrelay ,;may becommon to the lines of a-group of.-subscriberslines and when its armatureisiattracted a.ci'rcuit is established which 1s, traceable from the grounded battery 10''- through the-circuit interrupter 11, the arma:

ture of relay 9 and its contact, contacts of an operators switch 9 when closed the lowermost armature switch of relay '12 and itsnormal contact; the motor magnet 13,-, to

ground. The circuit of the motor magnet,

13 is interrupted so that its armature moves the ratchet .wheel 14* that. carries wipers "15,

16,117, 18 and-1 9;that pass over sets of waiting contacts belonging to. the group of telephone lines having the relay 9, there being two sets of such waiting contacts indicated at 20, 21, 22,23, and 24. When a subscriber initiates a, call a circuit connection is estab lished for the waiting contact 24' belonging, to his line which circuit connection may be; ,traced'from the contact 24: of the calling,

line, the lowermost armature switch of relay 6 and its then engaged'contact the follow-up contact of the armature switch immediately above the core ofrelay 8, the upper winding of the relay 8, to the grounded battery .10. That is potential is placed upon the waiting contact 24: of. a calling line by connecting the grounded battery 10 therewith, the contacts 24 of non-calling lines being clear of such potential. When the wiper 19 engages the contact 24 having this potential the circuit connection just traced has a continuation that establishes a closed circuit which continuation includes the wiper l9, the

follow-up normal contact of the upper armature switch of relay 12, the winding of relay 12, the contacts of an operator switch 9 when closed, the upper armature switch of relay 25 and one of its contacts, to ground. Thus the magnet 12 becomes energized andits upper armature switch leaves its normal follow-up contact into engagement with its alternate contact to establish a locking circuit through the magnet 12 and at the same time the lower armature switch of relay 12 is removed from its normal contact to open the circuit of motor magnet 13 whereby the wipers upon the actuated ratchet wheel 14 (the wipers 15 to 19 inclusive) are arrested. The locking circuit established by the magnet 12 may be traced from the grounded battery 10, the upper winding of relay 8, (the armature switch immediately above the "core of this relay having left its normal follow-up contact and now engaging its alternate contact owing to the circuit initially establishedfor this relay 8 at the lowermost armature switch of the previously energized relay 6), the armature switch immediately above the core of relay 8, the alternate contact of this armature switch, the waiting contact 21 of the operated wipers, the wiper 16 engaging'this waiting contact, the upper [armature switch of relay 12,-contaots of an {operators switch 9? when closed, the upper iarmature switch of relay 255-and one ofits '5 normal contacts, 1 to-ground. The locking circuit for the up er ,winding of relay 8 continues through its armature switch immediately' above its core, the alternatecontact ofzthis armature switch, both sides of the calling..-;subscribers line,- th'erelay 6, to ground.-: Gne side of'each telephone line is permanently connected with the talking waiting contact 21 and theotherside of each subscribeids line is connected with the talk- ;ingwaiting contact 20 when next to the upper armature switch of relay 6 is attract- ;ed. Thus the-talking waiting contacts 20 l and 2-1 are connectediw-ith the talking wipers v iself-to the manner in which communication V is established between calling subscribers and the operators. The selector switches herein shown are individual to the'operators positions, thereby being common to a plurality of lines. There are present means for electrically difi'erentiating calling from non-calling lines whereby the selector switches individual to operators positions are arrested. That is in a calling line the lowermost contact 24 is connected with the lowermost armature switch of relay 6 with the results which have been described whereas in non-calling lines the waiting contacts 2 L remain disconnected.

Having ascertained the desired number the operator depresses a plunger 28 of a key associated with a connector switch that will enter into the connection between the calling and desired lines. The operator next depresses the plunger 29 of a key or switch that will effect the connection of the calling line with one end of a link connector, the other end of which is to be connected with the desired line by means of the connector switch governed by the switch having an actuated plunger 28. WVhen the plunger 29 is depressed a circuit is established which may be traced from the'grounded upper armature switch of relay 25, the right hand contact of this switch, the contacts 30 closed by the operation of the key 29, contacts of switch 9 when closed, the actuated wiper 18, the waiting contact 23 engaged thereby, the lowermost armature switch of relay 8 and its then engaged contact, the lowermost armature switch of relay 31 and its then engaged contact, the WiIICllDg'Of the motormagnet 32 Sbelonging to the switch that is to connect 1e calling line with the talking wipers 33, 34:. at one end'of a link ccnnector 25, at Whose other end the talking wipers 36 and 37 are located and which are to be employed for connectionwith the waiting contacts of the desired line or line extension) the constantly operating interrupter 11 to the grounded battery 10. The motor magnet 32 now operates the ratchet wheel 39 to move the wipers 33, 3a and an extra wiper 40 around until the wiper .40 engages a grounded contact 41 whereupon the wipers 33, 34 and 40 are arrested with the first two ing contacts 4:2 and 43 belonging to the calling line. Thus there is provided a call:'- ing line selector switch common .to the telephone lines of a group. The contacts 4:1. pertaining to the telephone lines'are grounded, when such lines are calling lines, by a path which is traceable from the grounded coil of relay 25-, the intermediate armature switch of relay 25 and its normal follow-up contact, the left hand contacts of key 29, contacts of key 9 when closed, the actuated wiper 17 belonging to the selector switch that was actuated by the calling subscriberv when the call was initiated, the waiting contact 22 engaging this wiper, to the extra waiting contact 41 individual to the calling line. This circuit portion, when engaging the wiper 4:0, is included in circuit with the upper armature switch of relay 31 and its normal follow-up contact, the winding oi this relay, the previously closed switch ea,

and the grounded battery 10; The magnet 31 is thereupon energized to depress the wipers carried by the ratchetwheel 39 to depress the wipers 33, 34 into' engagement with the selected contacts l-2' and 43, the magnet 31 in being energized causing its armature switches to be actuated, the circuit of the motor magnet 32 being opened at the lower armature-switch of relay 31. The upper armature switch of this relay engages its alternate contact before leaving its normal contact and thereby establishes a locking circuit for the relay which may be traceable from the grounded battery 10, the closed switch at, the winding of relay 31, the uppermost armature switch of this relay and its alternate contact, the wiper 34:, the waiting contact 43 engaged by this wiper, the armature switches 7 of the calling line and their normal contacts together with the calling line included between these armature switches, to the grounded winding of relay 6. The circuit which was previously traced through the relay 25 caused the energization of this relay and the establishment of a circuit traceabl from the grounded coil of the relay, its intermediate armature switch and the alternate contact of this armature switch, the previously closed switch 45, to the grounded battery 10. This circuit, which is a locking circuit for the relay 25, maintains the relay 25 energized thereby to remove the upper armature switch of this relay from its contacts, ground being re- I interrupter 11, the motor magnet L? of a of these wipers in engagement with the wait connector switch, the lowermost armature switch of relay 4:8 the next to the upper strand of the link connector 35, the wiper line, to' the grounded coil of this relay. The

motor magnet 41-7 is then started into operation, the initlal result being theclosure of the switch 48, a circuit being established when the wiper 50 engaged the waiting' conjtact 51 of the called'line and which ci'rcii is traceable fromv the battery 49, thelewe most armature switch of relay 25', the'le hand contacts of switch. 29, contacts switch 9 when cl'osed, "the wiper 1?, Waiting contact 22, the waiting contact the wiper 4O verng'aging'the, same, the .lowe l most strand of the .l nkfconnector 35, the;-

upper windingflof re p 50, the wait ng conta called iine,

a ass beneath and closed by the actuated plunger 1 37 into eng .28, the winding of relay 52, to the battery 49, the key 28' being restored. The relay 48 is now energized to bring the wipers 36,

ement with the waiting cont'acts '53, 54 o the desired lirie.

When the relay 48 is energized a locking circuit is established therefor which is traceable'from thegroundedbattery 10, the lower winding of relay 48 the upper armature switch of this relay, the lower intermediate strand of the link-connector 35, the wiper 34, the. waiting contact 43, both sides of the calling line by way of the armature switches ofringing relay 7 and their normal contacts, to the grounded relay 6. The circuit for the motor magnet 47 is opened at the lowermost armature switch or relay 48 so that this motor magnet discontinues its operation. Thusby means of the key 28 the range of operation of the connector switch having the motor magnet 47 is determinedso that its wipers are moved into cotiperative relation with the waiting contacts of the called line. When the key 28 was depressed the horizontal limb of the switch lever 55 entered the notch of the key stem to'hold said stem in a depressed position and thereby retain the contacts beneath the stem in engagement. When magnet S of the called line is energized a locking circuit is established .therethrough which may be traced from the grounded battery 10, the upper winding of relay 8, the armature switch immediately adjacent the core of this relay, the alternate contact of this armature switch, the waiting contact 54 of the called line, the wiper 37 engaging the same, the companion wiper 34;, the waiting contact 43 engaged by the wiper 34, both sides of the calling line, to the grounded relay 6 of the calling line.

The foregoing description has beeniurnished with the assumption that either of the switches 9 is in a closed position while the other is in an opened position. As the drawings show the system the upper switch 9 is inposition to associate the operators telephone 27 with the upper selector switch, while the lower switch 9 is in an open position to cut off association between the operators telephone 27 and the lower selector switch. The upper selector switch will therefore be employed to associate the calling subscribers telephone outfit 27 with the calling line having station 120. The con trol of the electromagnetic devices having the motor magnets 32 and 47 for connecting link connectors with calling lines is efl'ected, in the example chosen, through the intermediation of the upper armature switch having the motor magnet 13 and the switch.-

ing device 9 individual thereto. The calling and called lines having been connected as above described, the, operator will, before releasing her upper key 9 depress her ringing key 56 that is individual to the employed (the upper) selector switch to bring the.

ringing generator 57 into circuit connection with the called line to ring the signal bell 4 at the called station. In view of the circuit arrangement illustrated the ringing key 56 is to be depressed before the key 29 is depressed. The ringing generator 57 has a terminal contact 58 forming a part of each switch 56 that are individual to the different selectors. These contacts 58 are provided with complemental contacts formingterminals of magnets 59.that are employed to maintain the generator 57 in circuit with the called lines until the called parties respond. by-removing'their telephone receivers from their switch hooks. When the selected key 56 has beenv depressed the spring pressed detent 60 (which was previously held against the stem of the key) enters the notch of the key so as to hold the key in its depressed position. The releasing magnet 59 has its armature extended into association with the detent 60 so that when the magnet 59 is 'energized, as it is when the calling subscriber responds, the detent 60 is withdrawn from the plunger notch of key 56 so that this key is restored to its normal position and the generator which was previously included in circuit at the contact 58 is excluded from circuit. The circuit over which current from the generator finds path is traceable from the grounded terminal of the generator, the spring 58 of the actuated key 56 and the contact then engaged thereby, the winding of the holding magnet 59, an extra wiper-61 provided upon the corresponding selector switch, the waiting contact 62 then engaged by the wiper 61, the waiting contact 63, the wiper 64 then engaging the same, the upper strand of the link connector 35, the wiper '65, the waiting contact 66 then engaged thereby, and belonging to the called line, the upper armature switch of relay 7 and its alternate contact, the switch hook 1 at the called station, the signal bell 4 at the called station, the condenser 5, the lower armature switch of relay 7 of the called line and its alternate contact, to ground,the relay 7 of the called line having been energized over a circuit traced from the grounded terminal of this relay through the winding of the relay, the lower intermediate armature switch of relay 6 of the called line, the uppermost armature switch of relay 8 of the called line and its then engaged contact, the interrupter 38, the battery 10, to ground. The bell bridges at the subscribers stations are of such resistance as sufiiciently to reduce the current flowing from the generator 57 to prevent the energization of the relay 59 thusfii'rcluded in circuit with the called subscribers signal bell.

When the called subscriber removed his telephone from its switch hook the low resistance telephonebridge at the called station is substituted for the comparatively high re-.

now elevated contact 581*of the employed key 56. By means of the interrupter 38 the relay '7 of the called line is intermittently energized so as intermittently to include the ringing generator 57 in circuit with the called sub'scribers" bell. If the called subscriber should happen to'remove his telephone from its switch hook during a period when his relay 7 is deenergized the magnet 59 will be effectively energized to remove the generator 57 from circuit relation with the called line by reason of a circuit traceable from the grounded coil of relay 6, both sides of the called line by way of the armature switches of the called subcore of the called subsc'ribers relay 8 and its alternate contact, the upper winding of this relay 8, to the grounded battery 10, the called subscribers relay 6 then closing a low resistance circuit for the magnet 59 which may be traced from the grounded uppermost switch of the called subscribers relay waiting contact 66 of the called line, the Wiper 65 then engaging the same, the wiper 64, the waiting contact. 63 then engaged by the wiper 64, the waiting contact 62 of the employed selector switch, and the wiper 61 then engaging'the same, the winding of magnet 59, the spring 58 of the actuated key 56 and its then engaged contact, to the grounded generator 57, the magnet 59 then operating to withdraw the detent- 60 from engagement with the notch of the plunger of key 56 to open the generator circuit at 58. When the key 56 is restored the ground pre viously established at this lowermost switch spring 67 is removed from connection with the holding magnet 12 so that this holding magnet is deenergized to permit the wipers of the selector switch that previously associated the operators telephone with the calling line to be restored to normal. All of the operations which have been described can be performed with the key 9 in either of its positions but inasmuch as it is desired to release the operators telephone 27 after the operator has performed her work in connection withestablishing the connection between calling and called lines, the upper key at one time, be brought into service keys 28 are brought into association with the 9 is" elevated to an open position after the key 28 is restored to normal whereupon the lower key 9 is shifted to that posit-ion in which the telephone outfit 27 is associated with the lower selector switch that may'then serve to associate this telephone outfit with another calling line. The operator maintains supervision over the connection being established until the key 28 is restored the restoration of this key serving to indicate to the operator that the wanted line is idle. When the called subscriber responds and the signaling generator 57 has been excluded from circuit the selector switch initially employed to associate the operators responsive device 27 with the calling line is restored to normal owing to the opening of the circuit for the holding magnet 12 be longing to this selectorswitch at 67.

When the subscribers are through conversation they restore their receivers upon their switch hooks whereby circuits through the magnets 6 of these lines are interrupted at y the switch hooks of the connected stations,

the operative connections previously'established at the armature switches of these relays 6 being broken whereby the apparatus v v is restored to normal, the magnets 31 and scriber's relay 7 and their normal contacts, the armature switch immediately above the i 48 releasing their associate ratchet wheels 39 and 4:8 to permit the wipers carried thereby to be restored to normal before the restoring movements of the upper armatures of these relays 31 and 48 have been completed, these relays 31 and 48 when energized, hav- 1 ing disengaged the actuating pawls of their associate motor magnets from their corre sponding ratchet wheels. 6 and the contact then engaged thereby, the

The keys 28 at an operators position,

i there are more than those illustrated at each position, are provided with a magnet 52 common thereto and the armature of thls magnet is common to all of the keys so that when any key of a group has been depressed it is associated by a common ma net 52. The switch levers 55, or in the lnstance shown the under switch lever 55, is serially related with the switch contacts beneath the switch plunger that is located above so that but one key 28 at an operators position may,

lines by means of magnets 8 and the selector switches as illustrated.

Fig. 3 indicates a delaying device by which the ratchet wheel is permitted to restore to normal prior to the return of the actuating pawl of the motor magnet to the position in which it may actuate the ratchet wheel. A delaying detent a is pivoted at b and is pulled upon by a spring 0 so as to have a position to engage the pawl d of the motor magnet when this pawl is raised by the finger e operated by the holding magnet when energized. l Vhen the holding magnet is de-energized the finger f fixed upon the The ratchet wheel strikes the holding pawl a, when the ratchet wheel has reached normal,

and released the holding pawl from engagetion between calling lines and calling line extensions or other telephone lines. By means of one of the systems disclosed in these co-pending applications calling line terminals are moved into connection with contacts of link connectors; in another system direct connection is effected between contacts belonging to calling lines and c0ntacts belonging to called lines; and in the remaining system contacts belonging to link connectors are moved into connection with contacts belonging to the calling lines.

While I have herein shown and particularly described the preferred embodiment of my invention I do not wish to be limited to the precise details of construction and circuit arrangement shown as changes may readily be made without departing from the spirit of my invention, but

Having thus described my invention I claim as new and desire to secure by Letters Patent the followin 1. A telephone exc l iange system including lines extending from telephone stations to an exchange; a plurality of link connectors at the exchange for uniting telephone lines; operators responsive devices; a plurality of selector switches adapted to associate free operators responsive devices with calling lines, the link connectors having operator controlled means to adapt them to their line joining function independently of the aforesaid selector switches operator controlled apparatus taking part-in establishing connection between calling and called lines and brought into operative association by the selector switches employed to connect op- .erators responsive devices with calling lines; and means for dissociating the operators responsive devices from the selector switches that have associated these responsive devices with calling lines and for transferring these responsive devices into association with other selector switches whereby the selector switches which were employed to associate operators responsive devices with calling lines may be continued in service to enable the operators to further connection between calling and called lines without interfering with the association of the opan exchange; a plurality of link connectors at the exchange for uniting telephone lines;

operators responsive devices; a plurality of selector switches common to a pluralityof lines and adapted to associate freeo' erators" responsive devices with calling. ines, the link connectors having operator controlled means to adapt them totheir line joining function independently of the aforesaid selector switches; operator controlled apparatus taking part in establishing connection between calling and called lines and brought .into operative association by the selector switches employed to connect operators responsive devices with calling lines;

and means for dissociating the operators responsive devices tram the selector switches that have associated these responsive de- Vices' with calling ,lines and for transferring these responsive devices into association with other selector switches, wherebygthe lector switches which were employedto associate operators responsive devices with calling lines may be continued in service to enable the operators to further connection between calling and called lines without interfering with the association of the 0perators responsive devices with other calling lines.

3i Atelephone exchangesystem including lines extending from telephone stations to an exchange; a plurality oflinklconnectors at the exchange for uniting telephone lines; operators, responsive devices; a plurality of selector. switches adapted to associate free operators responsive devices with calling lines, the link connectors having operator controlled means to adapt them to their line joining function independently of the aforesaid selector switches; automatically operaterator controlled means for setting. these linewselector switches into operation and associated therewith by the selector switches employed for associating operators respon sive devices with calling lines; and means,

for transferring the operators, responsive devices from the selector switches that have associated them with calling lines to associa-. tion with other selector switches...

4. A telephone exchange system including lines extending from telephone stations an exchange; a plurality of link conn ctors.

. ing ca1ling line selector switches for connect- 7 ing the link conectors with calling lines; op-

at the exchange for uniting telephone lines" operators responsive devices; a plurality of selector switches adapted to associate free operators responsive devices with calling lines, the link connectors having operator controlled means to adapt them to their line joining function independently of the aforesaid selector switches; automatically operating called line selector switches for connecting the link connectors with called lines; operator controlled means for setting these line selector switches into operation and associated therewith by the selector switches employed for associating operators responsive devices with calling lines; and means for transferring the operators responsive devices from the selector switches that have associated them with calling lines to association with other selector switches.

A telephone exchange system including lines extending from telephone stations to an exchange; a plurality of link connectors at the exchange for uniting telephone lines; operators responsive devices; a plurality of selector switches adapted to associate free operators responsive devices with calling lines, the link connectors having operator controlled means to adapt them to their line joining function independently of the aforesaid selector switches; a source of signaling current; means governed by the selector switches employed for associating operators responsive devices with calling lines for associating the source of signaling current with called lines; and means for transferring the operators responsive devices from the selector switches that have associated them with calling lines to association with other selector switches.

6. A telephone exchange system including lines extending from telephone stations to an exchange; a plurality of link connectors at the exchange for uniting telephone lines; operators responsive devices; a plurality of selector switches common to a plurality of lines adapted to associate free operators responsive devices with calling lines, the link connectors having operator controlled means to adapt them to their line joining function independently of the aforesaid selector switches; automatically operating calling line selector switches for connecting the link connectors with calling lines; operator controlled means for setting these line selector switches into operation and associated therewith by the selector switches employed for associating operators remeans for transferring the operators responsive devices from the selector switches that have associated them with calling lines to association with other selector switches.

7 A telephone exchange system including lines extending from telephone stations to an exchange; a plurality of link connectors at the exchange for uniting telephone lines; operators responsive devices; a plurality of selector switches common to a plurality of lines and adapted to associate free operators responsive devlces w1th calhng lines, the

link connectors having operator controlled means toadapt them to their line joining function independently of the aforesaid selector switches; automatically operating called line selector switches for connecting the link connectors with called lines; operator controlled means for setting these line selector switches into operation and associated therewith by the selector switches employed for associating operators responsive devices with calling lines; and means for transferring the operators responsive devices from the selector switches that have associated them with calling lines to association with other selector switches.

.8. A telephone exchange system including lines extending from telephone stations to an exchange; a plurality of link connectors at the exchange for uniting telephone lines; operators responsive devices; a plurality of selector switches common to a plurality of lines and adapted to associate free operators responsive devices with calling lines, the link connectors having operator controlled means to adapt them to their line joining function independently of the aforesaid selector switches; a source of signaling current; means governed by the selector switches employed for associating operators responsive devices with calling lines for associating the source of signaling current with called lines; and means for transferring the operators responsive devices from the selector switches that have associated them with calling lines to association with other selector switches.

A telephone exchange system including lines extending from telephone stations to an exchange; a plurality of link connectors at the exchange for uniting telephone lines; operators responsive-devices; a plurality of selector switches adapted to associate free operators responsive devices with calling lines, the link connectors having operator controlled means to adapt them to their line joining function independently of the aforesaid selector switches; and means for transferring' the operators responsive devices from association with employed selector :switches into association with unemployed selector switches. sponsive devices with calling lines; and

10. A telephone exchange system includ j ing lines extending from telephone" stations to an exchange; a plurality of link conjnectors at the exchange for uniting tele- Iphone lines; operators responsive devices;

a plurality of selector switches common to a plurality of lines and adapted to associate free operators responsive devices with-calling lines the link connectors 'ha'vingoperator controlled means to adapt them to their line joining function independently of the aforesaid selector switches; and means for transferring the operators responsive devices from association with employed seand means for dissociating the operators responsive devices from the selector switches that have associated these responsive devices with calling lines and for transferring these responsive devices into association with other selector switches whereby the selector" switches; which were employed to associate operators responsive devices with calling lines may' be continued in serviceto enable the operators to further connection between callin and called lines without interfering witht ie association of the operators responsive devices with other calling lines.

12. A telephone exchange system including lines extending from telephone stations to an exchange; a plurality oflink connectors at the exchange for uniting telephone lines; operators responsive devices; a plurality of selector switches common to a plurality of lines and adapted to associate free operators responsive devices with calling lines; operator controlled apparatus taking part in establishing connection between calling and called lines and brought into operative association by the selector switches employed to connect operators responsive devices with calling lines; and means for dissociating the operators responsive devices from the selector switches that have associated these responsive devices with calling lines and for transferring these responsive devices into association with other selector switches whereby the selector switches which were employed to associate operators responsive devices with calling'lines may be continued in service to enable the operators to further connection between callin and called lines without interfering with t e association of the operators responsive devices with other calling lines.

13. A telephone exchange system including lines extending from telephone stations to an exchange; a plurality of link connectors at the exchange for uniting telephone lines; operators, responsive devices; a plurality of selector switches adapted to associate free operators responsive dev ces with calling lines; automatically operat ng calling line selector switches for connecting the link connectors with calling lines; op

erator controlled means for setting these line selector switches into operation and associated therewith by the-selector switches employed for associating operators responsive devices with calling lines; and means for transferring the operators responsive devices from the selector switches that have associated themwith calling lines to association with. other selector switches.

14. A telephone exchange system including lines extending from telephone stations to an exchange; a plurality of link connectors at the exchange for unitingtelephone lines; operators responsive devices; a plurality of selector switches adapted to associate'free operators responsive devices with calling lines; automatically operating called line selector switches for connecting the link connectors with called lines; operator controlled means for setting these line selector switches into operation and associated therewith by the selector switches employed for associating operators responsive devices with calling lines; and means for transferring the operators responsive devices from the selector switches that have associated them with calling lines to association with other selector switches.

15. A telephone exchange system including lines extending from telephone stations to an exchange; a plurality of link connectors at the exchange for uniting telephone lines; operators responsive devices; a plurality of selector switches adapted to associate free operators responsive devices with calling lines; a source of signaling current; means governed by the selector switches employed for associating operators responsive devices with calling lines for associating the source of signaling current with called lines:

and means for transferring the operators responsive devices from the selector switches that have associated them with calling lines to association with other selector switches.

16. A telephone exchange system including lines extending from telephone stations to an exchange; a plurality of link connectors at the exchange for uniting telephone lines; operators responsive devices; a plurality of selector switches common to a phirality of lines adapted to associate free operators responsive devices with calling lines; automatically operating calling line selector switches for connecting the link connectors with calling lines; operator controlled means for setting these line selector switches into operation and associated therewith by the selector switches employed for associating operators responsive devices with calling lines; and means for transferring the operators responsive devicesfrom the selector switches that have associated them with calling lines to association with other selector switches.

17. A telephone exchange system including lines extending from telephone stations to an exchange; a plurality of link connectors at the exchange'for unitin telephone lines; 0 erators responsive devlces; a plurality o selector switches common to a plurality of lines and adapted to associate free operators responsive devices with calling lines; automatically operating called line selector switches for connecting the link connectorsv'vith called lines; operator controlled means for setting these lin e selector switches into operation and associated therewith by the selector switches employed for associating operators responsive devices with calling lines; and means for transferring the operators responsive devices from the selector switches that have associated them with callin lines to association with other selector swltches.

18. A telephone exchange system including lines extending from telephone stations to an exchange; a plurality of link connec-o tors at the exchange for uniting telephone lines; operators responsive devices; a plurality of selector switches common to a plurality of lines and adapted to associate free operators responsive devices with calling lines; a source of signaling current; means governed by the selector switches employed for associating operators responsive devices with calling lines for-associating the source of signaling current with called lines; and means for transferring the operators re- Copies of this patent may be obtained for sponsive devices from the selector switches that have associated them with calling lines to association with other selector switches.

19. A telephone exchange system including lines extending from telephone stations to an exchange; a plurality of link connectors at the exchange for uniting telephone lines; operators responsive devices; aplurality of selector switches adapted to associate free operators responsive devices with calling lines; and means for transferring the operators responsive devices from association with employed selector switches. into association with unemployed selector switches.

20. A telephone exchange system including lines extending from telephone stations to an exchange; a plurality of link connectors at the exchange for uniting'telephone lines; operators responsive devices; a plurality of selector switches common to a plu-' rality of lines and adapted to associate free operators responsive deviceswith calling lines; and means for transferring the operators responsive devices from association with employed selector switches into asso ciation with un-employed' selector switches.

In witness whereof, I hereunto subscribe my name this sixth day of August, A. D..

x ELMER R. CORWIN. Witnesses G. L. CRAGG, E. L. WHITE.

five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

